Ambient Noise Tomography of the Salina volcanic island, southern Italy, from nodal seismic data

Two months of continuous records from 40 three-component nodal stations deployed from late October to late December 2023 are used to reveal the subsurface structure down to 2 km depth beneath the Salina Island, in the Tyrrhenian Sea (southern Italy). We present the first 3D shear wave velocity model of a relatively small island of ~26 km² areal extension derived by ambient noise tomography. We calculate Green’s functions for the vertical components and the anti-causal and causal components were manually and separately inspected to obtain the group velocity dispersion curves via frequency-time analysis (FTAN). Using the Noisy Dispersion Curve Picking program (Granados-Chavarría et al., 2019) we obtain a total of 616 dispersion curves, from 0.25 to 4 Hz. Between each station-pair, we considered the distance along the relief instead of the great-circle distance, to take into account the abrupt topographic gradients crossing the two cone-shaped volcanoes of Salina, Monte dei Porri to the west and Monte Fossa delle Felci to the east, the highest peak of the entire archipelago.

Salina Island hosts a widely variability of volcanic activities (volcanic fissure, collapses, stratovolcanoes, dyke intrusions and diatremes) in a small area. Our model allowed us to image the most representative volcanic episodes that shaped the island: 1) the oldest and highly eroded Pizzo di Corvo in the westernmost region, 2) the volcanic fissure-type volcanic episodes of Pizzo Capo (northeastern region) and Monte Rivi in central Salina (which transits to a central-type activity), 3) the two main stratovolcanoes, Monte Fossa delle Felci and Monte dei Porri, and 4) the youngest activity at the northwestern region, the collapse of the Pollara depression.

This study is funded by the INGV Pianeta Dinamico project 2023-2025 CAVEAT (grant no. CUP D53J19000170001) supported by the Italian Ministry of University and Research “Fondo finalizzato al rilancio degli investimenti delle amministrazioni centrali dello Stato e allo sviluppo del Paese”, legge 145/2018.